Patent GB-1282005-A (GB)
Title: Apparatus and process for moulding articles made of thermoplastic foam particles
IPC: B29C67/04
Filed: 1969-08-22
Abstract: 1282005 Moulding expanded thermoplastics; laminating TORAY INDUSTRIES Inc 22 Aug 1969 [3 Sept 1968 (2)] 41964/69 Headings B5A and B5N [Also in Division C3] Expanded thermoplastics particles, which may be expanded by evaporatable or decomposable agents and may comprise thermoplastic foam waste, are heated to melt the surfaces thereof e.g. at 30‹ to 100‹ C. above the particle melting point, by hot air or inert gas and/or radiant heat during gravitational delivery from a storage hopper to opposed moulding rollers or endless belts which compress and fuse the particles together into sheets, or rods of circular or rectangular cross-section. The particles 2 may be delivered from the storage hopper 1 by a rotary valve 3, a bucket conveyer, an electromagnetic vibratory feeder, or an endless conveyer, to fall between spaced pipes 4 from openings whereof hot air is blown downwardly at 45‹. When moulding rods, the cross-section thereof may be defined by surface grooves in opposed rolls, and when moulding sheets the edges of an opposed roll or belt nip are confined by flat boards. The moulding compression may be effected by increasing the speed of successive roll pairs, or by decreasing the nip between successive roll pairs or between an opposed pair of endless belts. The particles may additionally be heated by hot air or infra-red between successive roll pairs, or the opposed rolls or belts may be heated to a temperature proximate, and preferably slightly lower than, the particle melting point. The moulded product is cooled either by blowing water or cold air thereover, or by cooled opposed roll pairs through which cold water is passed, or endless belts 7 on which cold water is blown and which rolls or belts draw the product from the moulding rolls or belts 5<SP>1</SP>, 6<SP>1</SP>. The moulded product may simultaneously be laminated to one, or between a pair of exterior webs 9 which may comprise the same material as the particles, a thermoplastic sheet or film, paper, fabric, or metal or wood plate which may also simultaneously be heated by the air heating the falling particles, or by passage over heated rolls 9. The moulding may also be effected between opposed horizontally directed endless belts, Fig. 3 (not printed). For moulding a rod, Fig. 4 (not printed), the gravitationally delivered particles pass into a vertical roller nip from an enclosure thereabove of greater cross-sectional area. Examples are given wherein; Example 1, cross-linked polyethylene foam particles of 0À03 s.g. are moulded to a sheet of 0À05 s.g. between opposed rolls; Example 2, non-crosslinked polyethylene particles of 0À04 s.g. are similarly moulded to a sheet of 0À075 s.g.; Example 4, soft polyvinyl chloride foam particles of 0À06 s.g. are moulded between endless belts to a sheet of 0À1 s.g.; Example 5, polyethylene and ethylene-vinyl acetate copolymer particles of 0À03 s.g. are simultaneously moulded between successive roll pairs and laminated to an exterior polyvinyl chloride material in imitation of leather; Example 6, polyethylene foam particles of 0À05 s.g. are deposited on a heated iron sheet to which they are moulded and laminated by opposed heated roll pairs. It is stated that particles are preferably of a volume ratio of 2 to 10 prior to and subsequent to foaming, are preferably from 0À01 to 200 c.c., and their maximum to minimum dimension ratio is from 1 : 1 to 30 : 1, preferably 10 : 1. Various known polymeric materials are also specified as comprising the foam particles.